US1958416A - Distillation of tar and recovery of products therefrom - Google Patents

Description

May 15, 1934- G. E. BRANDON DISTILLATION OF TAR AND RECOVERY OF PRODUCTS THEREFRQM Filed Dec. 14', 1926 4 Sheets-Sheet 1 W T INVENT-OR ATTORNEYS May 15, 1934. a. E. BRANDON 1,958,416

DISTILLATION OF TAR AND RECOVERY OF PRODUCTS THEREFROM I l: O

Q1 O O F k O W 0 Z, Bur/Wu INVENTOR BY I F ATTORNEY y 1934. a. E. BRANDON 1,958,416

DISTILLATION OF TAB AND RECOVERY OF PRODUCTS THEREFROM Fiied Dec. 14, 1926 4 Sheets-Sheet 8 M W INVENTOR B PM $5M mww ATTORNEYS ,May 15, 1934. 5 BRANDON 1,958,416

DISTILLATION 0F TAR AND RECOVERY OF PRODUCTS THEREFROM File dDec. 14 1926 4 Sheets-Sheet 4 57 W Z INVNTOR I ATTORNEYS Patented May 15, 1934 UNITED STATES DISTILLATION'OF TAR AND RECOVERY or monuo'rs THEREFROM George E. Brandon, Ironton, Ohio, assignor to The Barrett Company, New York, N. Y., a corporation of New Jersey Application December'H, 1926, Serial No. 154,746 13 Claims. (01. 20266) This invention relates to improvements in the distillation of tar and the production of pitch, and includes a new method of tar distillation and pitch production and an improved apparatus therefor. More particularly, the invention relates to improvements in the distillation of coal tar and the production of pitch at coal distillation plants, such as by-product coke oven plants.

In the ordinary operation of by-product coke ovens the gases produced by the coking operation pass from the individual ovens through individual uptake pipes and goosenecks to a collector main common to a battery of ovens. The coke oven gases leaving the ovens at a high tem- 15 pera'ture are cooled to separate tar constituents therefrom, the tar constituents being separated partly in the collector mains and partly in subsequent condensers. I

Coal tar produced at by-product coke ovens is commonly shipped or conveyed to tardistillation plants where it is subjected to distillation for the recovery of coal tar distillates and the production of pitch as a residue of the distillation.

The present invention enables the tar to be distilled and pitch produced directly at the byproduct coke oven plant without the need of a separate tar distillation plant and without transportation expense.

According to the present invention, the hot coke oven gases, as they come from the individual coke ovens, are utilized for the distillation of tar and the production of pitch therefrom by bringing the tar into intimate contact with the hot coke oven gases immediately after they leave the hot coke oven gases at a high temperature the tar is eflectively distilled, with separation therefrom of a greater or less amount of volatile oils, leaving a heavier tar or pitch as the product of the distillation. Moreover, the spraying of the tar into the hot coke oven gases results in cooling of these gases and separation of more or less of the heavier tar constituents therefrom which are thus added to the pitch residue from the tar distillation. The result of this method of distillation is to enrich the coke oven gases in oil vapors as well as to effect a partial or preliminary purification of the gases from heavier tar constituents, and to produce pitch from the tar at the coke oven plant.

In the practice of the invention, the tar to be distilled is sprayed or atomized into the hot coke oven gases, or is otherwise brought into intimate contact therewith, so that the hot gases can heat and distill the tar, andso that the gases will coke oven. By bringing the tar directly into the at the same time be cooled by the tar and enriched by the distilled vapors and cleaned from more or less of the heavier tar constituents which the gases themselves contain.

The individual coke ovens, according to the 69 present invention, are provided with gas. outlet pipes of a construction such as will enablethe tar to be sprayed or otherwise introduced directly into a stream of hot gas immediately after it leaves the coke ovens. The outlet pipe may advantageously be a modified uptake pipe, such as hereinafter described, in which the tar is sprayed or atomized into a rising stream of the hot coke oven gas While the gas is at substantially its maximum temperature. 76

The construction of the coke oven and of its by-product recovery system may otherwise remain unchanged, or with only such changes as are required to supply the modified outlet pipe 5 with a supply of tar and to draw off and collect the pitch or heavy tar produced by the distillation. For example, a modified uptake pipe can be substituted for the ordinary uptake pipe, leaving the connection of the uptake .pipe with the coke oven and with the collector main the same as in 80 present day construction. The vapors from the distillation of the tar in such case will be carried along with the coke oven gases and condensed and recovered in the recovery system. It is one of the advantages of the present invention that it is directly applicable to present day coke oven construction with a minimum of change in such construction and operation, while nevertheless enabling tar to be distilled and pitch produced by the use of heat contained in the hot coke oven 90, gases and without interfering with the operation of the coke oven or of its by-product recovery system.

In its broader aspects, however, the invention is not limited to the use of a modified uptake pipe in place of the uptakepipe of present day construction, nor is it limited to use in connection with the ordinary collector main and by-product recovery system. The coke oven gases containing the vapors'from the distillation of the tar may, instead of passing to the collector main, be separately treated for the recovery of oils, etc., therefrom. Such separate recovery is not, however, claimed herein, but forms the subject of a separate application Serial No. 158,137, filed December 31, 1926.

The tar which is distilled according to the present inventionmay be tar produced at the same coke oven plant at which it is distilled, or it may be tar from another source.

The tar may no direct contact with the hot vapors can be varied.

A suitable atomizing or spray nozzle, to which the preheated and thinly fluid tar is supplied under a 'sufiicient pressure to bring about atomizing or spraying and resulting intimate contact of the tar with the hot gases, can advantageously be located in the upper part of the modified uptake pipe to bring the tar into intimate contact with the hot gases.

A single tar spray can be used in each of the individual uptake pipes, or a plurality or series of such sprays, and the rate at which the tar is sprayed, as well as its temperature, can be regulated and controlled to obtain a greater or less degree of distillation of the tar and the production of a harder or softer pitch or pitch-like product.

The gases escaping from the top of a coke oven are at a high temperature, e. g., around 600 C. or in some cases even higher. The temperature of these gases is sufficiently high so that eifective distillation of the tar can be accomplished by an intimate and regulated spray of the tar into the hot gases. By employing .the gases at practically top-of-oven temperature their maximum heating and distilling eiTect is utilized. Depending upon the intimacy and time of contact of the particles of the tar spray with the gases, the temperature of the gases will be lowered to a greater or less extent and the tar will in turn be distilled to a corresponding extent. Efiective distillation can be accomplished with a temperature drop of the gases while passing through the tar spray of,

' by a considerable number of coke ovens.

for example, 106 (3., although with increased intimacy and time of contacta greater drop in temperature can be obtained. This decrease in tern perature is. advantageous in that it immediately cools the hot gases to a temperature such that little if any further decomposition therein takes place.

. The tar in turn will be heated by the hot gases and its temperature may be very considerably raised. Part of the heat of the gases, however, is employed in vaporizing liquid-constituents of the tar without corresponding increase in temperature of the tar, so that the maximum temperature of the tar and of the resulting pitchmay be considerably below that of the gases.

The amount of tar which can be distilled by th hot gases from a single coke oven is many times that which the coke oven itself produces, so that a single modified uptake pipe, when employed to distill tar according to the present invention, is capable of distilling the amount of tar produced As a result, a few modified uptake pipes, when employed for tar distillation in this way, are capable of distilling the entire amount of tar which a battery of coke ovens will produce. If all of the up take pipes of a battery are modified to distill tar in accordance with the present invention, the

amount oftar which can be distilled will be many times that which such a battery would produce.

From the standpoint of battery operation,

tery in accordance with the present invention.

Tar which is commonly shipped to tar distilling plants can insteadbe shipped to coke oven plants and there distilled as a part of the coke ovenoperation when modified according to the present invention.

With increase in the content of oil vapors of the coke oven gases, due to the distillation of the tar, and with the partial separation of heavy tar constituents from the gases by the tar spray, the resulting coke oven gases will be of different composition from those ordinarily obtained from a coke oven in which no such tar distillation takes place. When a large amount of tar is distilled in accordance with the present invention, the resulting coke oven gases will contain a correspondingly increased amount of vapors resulting from such distillation. In such cases the ordinary condensing systems may need to be changed to provide cooling or condensing capacity for separating the oils fractionally or otherwise, as desired.

When a battery of coke ovens, for example, a sixty oven battery, has a sufficient number of individual ovens provided with modified outlet pipe stills according to the present invention, and when the tar produced by the rest of the battery is subjected to distillation in these stills on the same battery, the vapor content of the gases will be increased and the condensing system and its operation can be correspondingly modified, if necessary, to provide for the recovery of such constituents. It is only necessary to modify a few of the individual uptake pipes, e. g., three to six uptake pipes to permit distillation of the tar produced by the remainder of the battery, e. g. of sixty ovens that is to say the gases maybe used for distilling from about 10 to 20 times their original content of tar, their distillation capacity varying of course with the melting point of the pitch produced.

In the carrying out of the process, the tar may be brought into contact with the hot gases once only or it may be recirculated and again passed through one of the uptake pipe stills to bring about further distillation and the production of a harder pitch. This further distillation may take place by recirculating the pitch through the same.

uptake pipe still, or through another or other stills, so that pitch of the same character and hardness is produced in the different stills or pitch of diiierent character and hardness in the different stills. By regulationof the rate of tar spray and its temperature of preheating, and by redistillation when necessary, it is possible to regulate the hardness of -.the pitch produced, and produce softer or harder pitches, as desired.

The invention will be further illustrated by the following more detailed description taken together with the accompanying drawings, which show apparatus embodying the invention and adapted for the practice of the process of the invention, but it is intended and will be under? stood that the invention is illustrated thereby but not limited thereto.

In the accompanying drawings, Fig. 1.is a view in elevation with part in section showing one form of apparatus,

with part of the ovens provided with the modified uptake pipes,

Fig. 3 shows a modification of the of Fig. l,

Fig. 4 is an enlarged view of one form of the modified uptake pipe, I

Fig. 51s a sectional view taken on ,the line 5-5 of Fig. 4, u

Fig. 6 is a sectional view taken on the line 6-6 of Fig. 4; and

Fig. 7 is a sectional view showing one form of spray nozzle.

The invention is of more or less general application to different types and constructions of byproduct coke ovens such as Semet-Solvay ovens, Koppers ovens, etc., but will be more particularly described and illustrated in connection with byproduct coke ovens of the Semet-Solvay type.

Fig. 1 illustrates the application of the invention to a single coke oven. The coke oven is illustrated conventionally at 1, and has the usual outlet 2 for the escape of the hot coke oven gases. The modified uptake pipe is indicated at 3 and connects at its upper end with the pipe 4 leading to a main 5 which may be the ordinary collector main. The uptake pipe 3, instead of being constructed in the ordinary way, is enlarged as indicated at 6 to provide a space around the inner upwardly extending pipe 7 which extends upwardly into the enlarged casing. Located within the casing above the end of the pipe 7 is a baffle or skirt 8, and above this in the upper part of the casing 6, or in the pipe 4 above the casing is arranged a spray head 9 connected Witha pipe 10 for supplying tar thereto. An outlet for pitch is located at the bottom of the enlarged casing 6 for discharging pitch from the space between the pipe '7 and the outer casing 6.

The construction and arrangement of the modified uptake pipe is such that it can be attached to the flanges of the pipe extending through the roof of the coke oven as indicated at 12 and so that at its upper end it can be connected to the pipe leading to the collector main as indicated at 13. This arrangement is such that little if any modification is required to.substit ute the modi fied uptake, pipe for that commonly employed in by-product coke oven construction.

The modified uptake pipe-construction illustrated in Fig. 4 has a series of doors or openings 14 near the bottom to permit inspection and cleaning and has an upper door 15 carrying the bafile or skirt 8, the arrangement being such that when the door 15 is opened the baflle 8 is removed from the casing 6. The uptake pipe is. also provided with overflow outlets 16 located some distance from the bottom. The pitch outlet 11 near the bottom of the uptake pipe construction is connected by means of a receptable 19.

The goose-neck connection to the collector main is shown as provided with spray nozzles 20 in the goose-neck and the collector main is also apparatus Pipe 18 to a pitch shown as provided with spray nozzles 21. Am-

mom'a liquor may beemployed in the spray nozzles 2D and 21 in the ordinary way. The main may be flushed with ammonia liquoras indicated at 22. Tar separated in the collector main is run to a suitable tar receptacle (not shown in Fig. 1) where the tar separates from the greater part of the ammonia liquor, leaving the tar still carrying more or less water. In Fig. 2 part of a battery of coke ovens is indicated at 28 with certain of the coke ovens being tion 3 and the others provided with uptake pipes 29 of ordinary construction. The cross-over main leading from the collector main to the coolers or condensers is indicated at 30 and the condensers or coolers at 31 and 32. The exhauster for drawing the gases through the system is indicated at 35.

The tar collected in the collector main and cross-over main is'shown as running to a tar collecting tank 23 in which the tar separates from the ammonia liquor, and this in turn is shown as leading to a dehydrator 24 for freeing the tar from water and preheatingit for use in the process. This dehydrator may be of any suitable construction. The preheated and dehydrated tar is pumped by the pump 25 through the tar supply pipe 10 to the spray nozzle 9.

In Fig. 3 the pitch receptacle 19 is shown as having a pipe 27 leading therefrom to the spray nozzle and a pump 26 in this line for recirculation of the pitch or tar.

One suitable form of spraynozzle is indicated in Fig. 7, this having an outer casing 36 with an inner core 37 having helical passages formed between it and the outer casing 36 and with the nozzle orifice 38. The construction is such that the tar is discharged with a whirling motion in the form of an exceedingly vfine voluminous conical spray. The tar, when it is preheated and thinly fiuidfmay be pumped to the nozzle under a suitable pressure, for example, 40 pounds per square inch and discharged through the nozzle so as to atomize or spray it into the hot uprising gas.

In the operation of the apparatus illustrated, and the carrying out of the process of the invention therein, the hot gases from the cokeoven pass upwardly through the modified uptake pipe and thence through the gooseneck to the collector main. The hot preheated tar is supplied in regulated amount to the spray nozzle and sprayed into the hot gases. The gases are brought into intimate contact with the spray of tar which is heated and distilled by the hot gases while the hot gases themselves are somewhat cooled. The tar is prevented from falling down into the coke ovens by the skirt or baffle 8 and collects in the space outside the pipe '7 and runs out through the pitch outlet 11. The action of the hot gases upon the particles of tar spray and upon the tar flowing down over the surfaces of the uptake pipe still is such that the tar is brought into intimate contact with the hot gases which serve to heat it and to distill volatile oils greater or less extent before spraying it into the hot gases, or by regulating the rate or character of spray, etc.

As illustrating one way of carrying out the process, the following example is given:

The tar used was that separated in a Semet- Solvay system. It was dehydrated and used in a preheated state, heated to around C. or somewhat higher. Upwards of 200 gallons of such tar were sprayed per hour into the hot coke oven gases and soft pitch of about 108 F. melting point obtained from the distillation. Pitches of higher melting point, e. g., 132 F. and higher have similarly been produced by regulation of the spraying operation. The gas from the ovens entered the uptake pipe at atemperature of about 600 C. and left the top of the uptake pipe 1 at a temperature in the neighborhood of 500 C. 1.50

-or until their fluidity-has decreased to a point v normally contained in the tar ried out in the apparatus illustrated, that the tar is subjected to a high temperature for only a short period of time, and the tar residue is not heated to the temperature of the hot gases, but escapes at a considerably lower temperature. Nevertheless, the tar is subjected to the heating and distilling action of the hot gases and is effectively distilled. As a result, a low carbon pitch can be directly produced without any appreciable increase in carbon content over that from which the pitch is produced.

Instead of passingthe tar only once into con tact with the hot coke oven gases, the tar or pitch produced therefrom can be recirculated one or moretimes through the same still, or passed through another or other stills, to subject it to further distillation and to produce a harder pitch. Instead of producing pitch of low melting point, around 108 F. harder pitches of higher melting point can be produced, for example, pitches melting at 140-150" F. (melting point by cube-in-water method) or pitches of melting point around 177 F., (air bath method) or pitch of 212 F. melting point, or even harder pitches which are sufiiciently fluid at high temperatures to permit them to be circulated until their melting point has been raised to the desired degree interfering with further'recirculation.

The gases after leaving the uptake pipe still at I a temperature around for example, 500 C. may

be further cooled by ammonia liquor sprays before reaching the collector main and also in the collector main so that the gases pass from the collector main to the cross-over main at a temperature e. g. below 100 C. The temperature of the gases leaving the cross-over main and entering the condensers or coolers, may be for example around '78 to C.

In the battery illustrated in Fig. 2, mostof the ovens are provided with uptake pipes of usual,

construction which may have ammonia liquor sprays in the goose-neck and in the collector main to separate a considerable amount of heavy tar in the collector main and to give gases of low temperature and contained heat of these gases to distill the tar and produce pitch therefrom. The provision of a few only of the coke ovens with the =modifled uptake pipe stills of the present invention permit these few stills to distill the tar produced by the rest of the b ofa sixty oven battery.

attery, even in case When the tar separated in the collector main is returned and redistilled in the manner described, the oil vapors'driven 011 from the tar during the distillation go back with the gases into the collector main and correspondingly increase the oil vapor content of the gases. If the tar so distilled is a heavy tar, the amount of vapors separated will be less than when the tar contains all or practically all. the condensible oils of the coke oven gases. That is, if a heavier tar 'is collected, and lighter oils or lighter tar-con taining oils are subsequently separated in the coolers or condensers, the heavier tar will contain less oils to be distilled than when all of the tar constituents are condensed together or subsequently mixed after condensation at several points in the recovery system. In the latter case, an increased amount of vapors will be distilled from the tar and the vapor content of the coke oven gases will be correspondinglyincreased.

By regulation of the temperature and operation of the collector main, most of the oils which it is desired to obtain can be thrown over into the condensers or coolers and there recovered in a form such that they do not need to be returned for further distillation. Some of the .oils will separate out with the tar in the collector main and will be returned to the stills forredistillation, but with the regulation of the distilling op-' eration and of the collector main operation, the amount of. oils thus requiring repeatedredistillation before they are separated in the condensers or coolers can be kept low.

It is not of course necessary to subject all of the tar produced by the coke oven batteries to.

redistillation in the manner described, but a part only may be so redistilled. So also, instead of. distilling tar from the same battery, tar produced by some other battery, or obtained from some other source may be distilled in a similar way.

The arrangement of Fig. 3 permits the recirculation of the tar or pitch one or more times to the same still'in order to subject it to repeated distillation to remove progressively more and more vaporizable oils therefrom and to produce a pitch of regulated degree of hardness. Tar which has been passed through the still once and collected as pitch may be again recirculated through the same or in a different still and the.

pitch from the recirculation kept separate,.and

this operation can be repeated as many times as may be desired. Or a large amount of tar can be recirculated and the pitch returned to the same batch with progressive distillation of the tar and increase in melting point of the pitch until I the'entire batch of tar has been converted pitch of the desired melting point. I

The uptake pipe and the circulatinglines, etc., are illustrated in the drawings in a conventional manner and without any insulation around them, but where it is desired to prevent loss of heat by radiation, or to reduce such loss, or to prevent unduecooling of circulating lines, etc., such circulating lines, and the uptake pipes and connecting pipes through which the gases pass,=can be provided with heat insulation.

into

Furthermore, the hot coal distillation gases from the coke oven can be cooled somewhat before. bringing them into contactwith the tar .provided their temperature is still sufliciently high'to bring about the desired distillation of the tar and the production of-pitch therefrom. It

is advantageous, however; to utilize the hotgases at their maximum temperature, immediately after they escape'from the coke ovens, by employing them in the manner described.

While I have described and illustrated a particular type and produce pitch therefrom.

2. A coke oven battery having means for separating and recovering tar from the coke oven ducing in said uptake pipes the dehydrated tar to distill the tar by direct contact With hot coke oven gases, and means for collecting and drawing oil? from said uptake pipes the pitch resulting from such distillation.

3. A by-product coke oven battery havinga of the battery, means for cooling the gases in said collector main with ammonia liquor spray, means for separating the tar from the ammonia liquor, means for drawing off tar and ammonia liquor from the collector main thereto, means for dehydrating the tar, means for supplying tar from the separating means to the dehydrating means, and means for supplying and introducing the dehydrated tar into at least one of the uptake pipes of the battery to effect dlsti11a tion of the tar by direct contact with hot coke oven gases and produce pitch therefrom, and discharging the coke oven gases with added vapors from such distillation into the common collector main. 4. The method of distilling tar in hot gases resulting from the distillation of coal in coke ovens which comprises spraying the tar into the gases at substantially the temperature at which they leave the ovens, in such regulated amount as to separate oil from the tar in the form of oil vapor and to leave a pitch residue and simultaneously removing pitch from the gases whereby a pitch pitch constituents present in' the tillation of the tar is produced and then cooling the gases to condense oils therefrom. V

5. The method of distilling tar in an uptake resulting from dis-- olf by the hot at a temperature not greatly below that at which they left the coal vdistillation chamber, and maintaining the tar in the form of spray in contact with the hot to 600 C. and maina sufiicient period of time so that a large part of the volatile constituentspf the tar is distilled gases.

13. The method GEORGE E. BRANDON.

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